Wave number of maximal growth in viscous ferrofluids.

A. Lange¹ - B. Reimann² - R. Richter²

¹ Universität Magdeburg, Institut für Theoretische Physik, Postfach 4120, D-39106 Magdeburg, Germany
² Universität Bayreuth, Physikalisches Institut, Experimentalphysik V, D-95440 Bayreuth, Germany

Abstract
Within the frame of linear stability theory an analytical method is presented for the normal field instability in magnetic fluids. It allows to calculate the maximal growth rate and the corresponding wave number for arbitrary values of the layer thickness and viscosity. Applying this method to magnetic fluids of finite depth, the results are quantitatively compared to the wave number of the transient pattern observed experimentally after a jumplike increase of the field. The wave number grows linearly with increasing induction where the theoretical and the experimental data agree well. Figs 2, Refs 13.